Thusis (Italian: Tosana, Romansh: Tusàn) is a municipality in the district of Hinterrhein in the Swiss canton of Graubünden.
Thusis is first mentioned in 1156 as Tosana.
Thusis has an area, as of 2006, of 6.8 km2 (2.6 sq mi). Of this area, 18% is used for agricultural purposes, while 58.2% is forested. Of the rest of the land, 15.2% is settled (buildings or roads) and the remainder (8.6%) is non-productive (rivers, glaciers or mountains). The municipality is the capital of the Thusis sub-district, of the Hinterrhein district. It is the center of the Hinterrhein valley and is located at the confluence of the Hinterrhein and Nolla rivers. Thusis is also at the end of the Viamala canyon. It consists of the village of Thusis and, since 1875, includes Übernolla.
Thusis has a population (as of 31 December 2014) of 2,994.As of 2008, 23.6% of the population was made up of foreign nationals. Over the last 10 years the population has grown at a rate of 0.7%.
Thusis is a railway station in Thusis, Switzerland. It is the terminus of the Landquart-Thusis railway line. Hourly services originating from Chur on that line also continue along the Albula Railway line to St. Moritz.
The Kreis Thusis forms, together with the sub-districts of Avers, Domleschg, Rheinwald and Schams, the Bezirk ("district") Hinterrhein of the Canton Graubünden in Switzerland. The district office is located in Thusis.